New Zealand are set to rest at least four key All Blacks for Saturday's Tri-Nations clash against South Africa.

Aassistant coach Wayne Smith has confirmed that Crusaders forwards Brad Thorn, Owen Franks and Kieran Read and Blues hooker Keven Mealamu will all be released from the All Blacks squad this week to recuperate from tiring Super Rugby campaigns.

Smith insists the All Blacks are committed to managing the workload of the players in the run up to the Rugby World Cup that starts in September.

"We're just sticking to the plans that we've got," Smith told NZPA. "So every player is on an individual plan and some are champing at the bit to get out and play, some are a wee bit overcooked so we're just sticking to that, making sure that we look after people.

"Our experience is that you're better to put the ones that are champing at the bit out there. We're about winning Test matches and the hungry players, the ones that are fresh and ready to go, they'll be playing."

South Africa coach Peter De Villiers was criticised by former Springboks coach Jake White for resting players for last weekend's 39-20 defeat to Australia. With the more than 20 Springboks left in South Africa, both sides are set to be understrength for the clash in Wellington on Saturday. But Smith insists the All Black's situation is very different to the policy chosen by the Springboks.

"You can't really compare our situation to what the Springboks have done," he said. "The Springboks have made a choice to rest a big group of players. We're making individual choices on who's ready to play this week to win the Test match and we're sticking to that."

Following the Tri-Nations, New Zealand face Tonga in the opening of the game of the World Cup on September 9 and Smith says the decision have been made in conjunction with the players.

"It's not so much what they're saying, it's more what we've observed and experienced in the past and also understanding what we've coming up, so it's a joint decision," he said.

"There are still a few that have done a lot of travel, who have played a lot of footy, who have got young families - who have been through a lot - who still need a wee bit of time to themselves."